Currently, I am using a Sony digital camera that is so thin, it fits in my pocket of a top or jeans or, can fit in a bra. It has a slide mechanism that turns on the camera almost immediately and a battery that lasts for days. The camera is set to take photos as required by the many MSCs. It is my second one of this type. When my first finally fell apart after dropping it in airports, shops, etc, I found the exact one on eBay for less than $30.
Besides that one, I carry with me, at all times, 5 additional digital cameras, all with fully charged batteries. I carry them for any contingency where my primary camera fails. All of them are no larger than a deck of cards. All of them were purchased for less than $10 from resale shops. They may have come without a battery, chip or charger. But all of those items can be found an purchased on websites such as Amazon.
I always bring my laptop with me and download and name my photos to the laptop in the specific file for that shop's location. In the event of a catastrophic failure of the laptop, I have a backup at home with the identical files of my shops (just not up to date photos). If my laptop fails while on the road, my camera's memory is large enough to hold all the photos of the shops I am doing on the road. I separate each shop by taking a photo of my worksheet after all of the shops photos are taken.
Is that being overly cautious? Maybe. But, I'm not about to travel any distance only to find that my camera is dead or my laptop is acting up and my cell is the alternative.